Synthesis of plait-like carbon nanocoils in ultrahigh yield, and their microwave absorption properties

Over Ni nanoparticles generated by means of a combined sol-gel/reduction method, crystalline plait-like carbon nanocoils (CNCs) were synthesized in acetylene pyrolysis at 415°C. The field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HR-TEM) images reveal that there are often two CNCs in opposite handedness fused in one nanoplait. By optimization of reaction parameters, maximum purities and yields of plait-like CNCs and single CNCs were 99.35 wt % and 99.53 wt %, and ca. 18759.8% and 21269.6%, respectively. The pyrolysis of acetylene was carried out at 415°C, and no dilute gas such as argon and nitrogen was needed. Thus, we have provided a simple, low-cost, and environmentally friendly approach for the mass production of CNCs with ultrahigh purity. The microwave absorption properties of the as-prepared plait-like CNCs and single CNCs were examined systematically. The results demonstrated that the as-prepared plait-like CNCs exhibit good microwave absorbing ability. The effects of the temperatures for acetylene pyrolysis and for NiO powder reduction in the CNCs synthesis on the morphology, yield, and microwave absorption properties of carbon products were also investigated.